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(11) | EP 0 716 370 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | A disk access method for delivering multimedia and video information on demand over wide area networks |
(57) A method and apparatus for delivering multimedia video data from a server (host processor)
to a plurality of clients connected to a communications network. More specifically,
with this invention, preprocessed video and multimedia data packets are striped across
disks in units of fixed playback time, even if such units result in variable length
stripes. To deliver multiple video or continuous media streams, the disks in the array
are accessed simultaneously so that at any given instance, different disks are accessing
the video or multimedia data for different streams. Access to the disks for reading
the continuous media files is scheduled periodically, with the period equal to the
back time of the stripes. Because each disk read command retrieves data for a fixed
play back time, if the first read command for a continuous media stream request can
be scheduled to complete on a disk within a playback time, all subsequent read commands
are also guaranteed to not interfere with read commands of other streams. Data is
delivered directly from the disk array to the communication network by a stream controller
without being sent to the host system. Disk storage is utilized efficiently by allocating
disk space in units of cylinders and storing the variable size stripes of video in
packed format. |